Japanese Patent Publication No. 3,618,939 discloses an apparatus for successively making plastic bags each of which includes a panel portion and a zipper portion.
In the apparatus, upper and lower webs of film material are superposed with each other. The apparatus includes upper and lower heat seal bars between which the upper and lower webs of film material are directed. Upper and lower bodies of zipper material are directed between the upper and lower webs of film material. The webs of film material and the bodies of zipper material are fed longitudinally thereof and intermittently. A receiver plate is interposed between the upper and lower bodies of zipper material. The upper heat seal bar is lowered toward the lower heat seal bar whenever the webs of film material and the bodies of zipper material are fed intermittently so that the webs of film material and the bodies of zipper material are sandwiched between the heat seal bars and the receiver plate. Accordingly, the upper web of film material and the upper body of zipper material are heat sealed with each other while the lower web of film material and the lower body of zipper material are heat sealed with each other, to successively make the plastic bags of the webs of film material and the bodies of zipper material. The webs of film material comprise webs of panel material which are plastics. The bodies of zipper material are also plastics. The panel portion is formed of the webs of film material. The zipper portion is formed of the bodies of zipper material. The bodies of zipper material may be called bodies of chuck material. The zipper portion may be called a chuck portion.
In addition, the apparatus includes a support plate extending widthwise of the webs of film material to protrude on opposite sides of the webs of film material, the receiver plate being fixed to the support plate. The apparatus further includes drives comprising air cylinders which are disposed on the opposite sides of the webs of film material and connected to the support plate so that the receiver plate and the support plate are carried by the air cylinders. It should therefore be understood that the apparatus constructs a double-support structure for the support plate. The receiver plate and the support plate are then raised by the air cylinders so that the receiver plate is moved away from the lower heat seal bar after the webs of film material and the bodies of zipper material are heat sealed with each other and when the upper heat seal bar is raised and returned to an original position. The webs of film material and the bodies of zipper material are therefore lifted by the receiver plate which is raised so that the lower web of film material is torn off the lower heat seal bar. The webs of film material and the bodies of zipper material are then fed again and intermittently. The webs of film material are therefore fed intermittently in a torn off state, without advancing obliquely or tortuously.
However, in the apparatus, the support plate has to protrude on the opposite sides of the webs of film material. In addition, the support plate has to be carried and raised by the drives disposed on the opposite sides of the webs of film material. The apparatus is therefore complicated in structure and high in cost.
Furthermore, the upper and lower bodies of zipper material are directed between the upper and lower webs of film material which do not always comprise the webs of panel material. For example, Japanese Patent Publication No. 4,526,592 discloses an apparatus for successively making plastic bags in which one of the upper and lower webs of film material comprises a web of panel material while the other web of film material comprises a web of bottom gusset material. The upper and lower bodies of zipper material are directed between the web of panel material and the web of bottom gusset material so that a bottom gusset portion and a bottom protrusion are formed of the web of bottom gusset material, the zipper portion being formed in the bottom protrusion.
In this case, the receiver plate may be interposed between the upper and lower bodies of zipper material and fixed to the support plate, as in the case of the apparatus of Japanese Patent Publication No. 3,618,939. However, the support plate cannot protrude on the opposite sides of the web of panel material to construct the double-support structure for the support plate. The support plate can merely protrude on one of the opposite sides of the web of panel material to construct a cantilever structure. It is therefore difficult to make the receiver plate and the support plate raised by the drive. Accordingly, the lower web of film material is not torn off the lower heat seal bar after being heat sealed. The webs of film material are then fed intermittently as they are, to advance obliquely or tortuously.
Each of Japanese Laid-Open Patent Publication No. H08-118,521, Japanese Laid-Open Patent Publication No. H10-31,535 and Japanese Utility Model Publication No. S43-19,033 discloses an apparatus for successively making plastic bags, which constructs the cantilever structure for the support plate. In addition, the upper and lower heat seal bars are lowered and raised respectively so that the webs of film material and the bodies of zipper material are sandwiched between the heat seal bars and the receiver plate. Accordingly, the upper web of film material and the upper body of zipper material are heat sealed with each other while the lower web of film material and the lower body of zipper material are heat sealed with each other. The upper and lower heat seal bars are then raised and lowered respectively so that the upper and lower webs of film material are torn off the upper and lower heat seal bars.
However, in order to make the upper and lower heat seal bars lowered and raised respectively, drives are required respectively. The apparatus is therefore complicated in structure and high in cost.
It is therefore an object of the invention to provide an apparatus for successively making plastic bags each of which includes a panel portion and a zipper portion, to be simple in structure and low in cost.